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daniel_i_l

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Thanks.

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- Thread starter daniel_i_l
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- #1

daniel_i_l

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Thanks.

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sylas

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Thanks.

That's a great idea... but, yes, it has been done, by students at Aarhus University. They have a blog about it, at Lego of Doom, including a video of it in operation.

Cheers -- sylas

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daniel_i_l

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sylas

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That would be very cool! Good luck.

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What exactly is a turing machine? I saw it one here and visited wikipedia. Is it basically a device that can perform a logical sequence of instructions with or without the need for a computer processor. So a completely mechanical turing machine would run on some sort of fuel, but actions and triggers etc. would be mechanically stored somehow?, like via a complex series of gears or switches?

Glad to be hear and I would love to hear anyone's feedback.

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CRGreathouse

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What exactly is a turing machine? I saw it one here and visited wikipedia. Is it basically a device that can perform a logical sequence of instructions with or without the need for a computer processor.

It's a mental experiment. There's no point* to building a 'standard' mechanical Turing machine, though every computer simulates one in a certain sense.

* Except for a cool project like this, of course.

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That's a great idea... but, yes, it has been done, by students at Aarhus University. They have a blog about it, at Lego of Doom, including a video of it in operation.

Cheers -- sylas

WoW I saw the video, so cool.

I would love to see the fully mechanical lego turing machine

- #9

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I believe the analytic and difference engines designed by Babbage were entirely mechanical as well, although I don't think they were quite universal turing machines (namely, not completely general purpose).

- #10

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Is a Turing machine the same as a universal Turing machine?

- #11

sylas

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Is a Turing machine the same as a universal Turing machine?

A universal turning machine is a set of transition tables for a turing machine. It means any other turing machine can then be encoded on to the tape, and simulated.

A concrete representation in lego becomes a universal machine given the right transition tables. If the transition table is maintained on a computer chip, as in the Aarhus machine, there is no problem making it into a universal turing machine, although actually encoding a non-trivial machine onto the lego tape might be too big. If the transition tables are maintained in lego as well, then the universal machine transition tables might be more than you'd like to build.

Cheers -- sylas

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It's basically what all computers emulate :) The encoding for a universal turing machine is pretty hefty though. I think I've seen a decimal encoding of a universal turing machine number (so an n in T

- #13

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I seem to recall some rendition of a UTM that required only 22 or 24 quintets. (I haven't looked at this stuff since Turing died.)

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The main problem, as I see it, is where will you put the infinite-length tape?

- #15

daniel_i_l

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Hi,

In the end lego was too expensive so I used carboplast, popsicle sticks, plastic bottles, rubber bands and a glue gun. Here's the result:

The turing machine in the movie can run down the track and flip bits according to a program determined by the wiring. Currently it can only execute simple programs because it doesn't have external memory. But that's theoretically simple to add because I'd just have to build another identical unit that operates on one bit only for each bit of memory.

In the end lego was too expensive so I used carboplast, popsicle sticks, plastic bottles, rubber bands and a glue gun. Here's the result:

The turing machine in the movie can run down the track and flip bits according to a program determined by the wiring. Currently it can only execute simple programs because it doesn't have external memory. But that's theoretically simple to add because I'd just have to build another identical unit that operates on one bit only for each bit of memory.

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